Category Archives: Mechanical

I was reviewing finances and made an executive decision. I cleaned up the head gasket to see what condition it was in.

Cylinder head gasket, block side (copper)

As it turns out, really very good shape. I figured I’d reassemble the engine using it- which isn’t really a very good idea, but changing the head gasket with the engine installed in the car is a simple task so down the road it can be done with ease.

I purchased a roll of 1/32″ gasket paper from NAPA up the street. I began tracing out the water pump gasket to create a new one, as the original was in poor shape.

RTV sealant

I found the tube of RTV (room temperature vulcanizing) sealant I had bought to redo the GTA’s engine. Still in good condition as it is actually really very high quality stuff.

A light smear of sealant added to the water pump back-plate face to aid in sealing, as the surface is only moderately good.

Gasket applied, sealant to the other side and torqued down to the engine block again.

I ran a die through the threads of the manifold studs to remove rust and dirt. This aids in reassembly quite significantly as once the manifolds are on, access to the nuts is limited, and being able to spin the nut on with one finger is a help.

I’m not totally sure what happened to this stud, but there are signs that the engine had fallen over at some point. Either way, the metal surrounding the hole for it was distorted. This was leaking through into the exhaust port (the hole goes through to the water gallery behind) and had caused the valve to stick.

I gently filed the surface to try and make it flush.

You can see the high spots around the stud hole, looks like it’s been leaking for a while judging by the amount of rust. The surface is now only recessed, rather than raised. The recessed sections are not very deep at all, so a new gasket should now be able to seal properly rather than being lifted off the surface by the high points.

I then set about cleaning up the head bolts with a steel brush and die. Cleaned the head and shank first, ran the die down the threads to clear them, then wire-brushed the threads before giving each bolt a light coating of engine oil.

Repeat x30.

With the deck of the block cleaned, I placed the head gasket down.

Then cleaned the head and laid it down onto the gasket, aligned it and did all the bolts up finger tight. I then added the spark plugs to prevent any dirt falling through the holes into the engine.

Taking a copy of the factory manual’s tightening sequence, I first did all the bolts up to 25 lb/ft to gently settle the head down, then did them all up to their final torque of 60 lb/ft.

I made some (admittedly far too thin) gaskets up for the manifolds. I need to order a set of the correct metal/composite sandwich gaskets, which are nearly 1/8″ thick.

I refitted the manifolds, carburetor, vacuum line for the distributor, spark plug cap and wires, coil, fuel pump and blocked the vacuum port on the manifold with a bolt. I hacked together some pipework for the fuel pump, to test and see if it was going to operate. Took a little while to prime but it did draw fuel successfully through.

It started up and ran nicely. I did see that the gearbox is not leaking from the tailshaft, rather from the engine end of the casing, possibly the front seal where the torus connects.

I then cleaned up the thermostat housing, the head surface and added a little black enamel to the bolts and washers.

Spent a little time bending and hammering the bracket for the air filter assembly. With the engine removed from the car, access is greatly improved and I was able to see underneath to measure and adjust the bracket correctly. I learned also that the air filter sits much closer to the engine than I had originally thought.

I dug a tachometer I had out of storage- I bought it way back in 2004 from a now-defunct store in the UK and brought it with me.

Connected it up and presto! It reads nicely- it’s even more accurate if I select it to 4-cylinder. The gearbox bands need to be set with the engine running at 700 RPM, so it’s important I have a working tachometer. It’s also much easier with an electronic one, rather than having to hold a mechanical one to the crankshaft pulley. Plus, I cannot see that AND adjust the gearbox at the same time…

The fuel pump has become a little wet around the seams too, so that needs a new gasket.

Finally, I fitted the thermostat housing to check for clearance between it and the air filter.

There was a moderate amount of carbon buildup in the combustion spaces. The cylinders nearest the center show heavier deposits, of which the deeper sections were a nice deep brownish red, indicating good running conditions. The outer cylinders had a darker color, indicating a different mixture burn. This makes sense due to the style (and length) of the manifold, with the carburetor in the center. The manifold was also not tightened evenly when I got the car and was not sealing uniformly.

VIN

Scraping off the paint and wire-brushing the surface liberated the VIN stamping, which matches the plate riveted to the body. A=Atlanta assembly plant, 8=8 cylinders, U=1951, H=Hydramatic automatic gearbox, 4381=serial

Top end clean

I cleaned the carbon deposits off the cylinders and valves. One valve had stuck open- the exhaust valve on cylinder no. 8- the result of a leaking gasket. It had drawn coolant in and made the valve stem jam in the guide. Gentle, repeated force and penetrating oil freed it up.

Dirty threads.

The head bolts all required very different amounts of effort to undo. Most of the bolts go through the top of the deck into the water gallery, and were both full of sludge and old sealant.

Tap.

I ran a 7/16″ 14TPI (standard coarse) tap through the holes to clean them up. As the head bolts are tightened to a torque, the threads need to be clean in order for the torque reading to be correct. A dirty thread will increase the amount of torque required to turn the bolt and as such, the bolt will not have the correct clamping force applied to it.

Dirt removed

This procedure removed a lot of dirt, but also started to dull my tap. The original sealant was white lead, which is incredibly hard. I shall be using a more modern sealant designed for sealing threads that go through into coolant.

Clean thread

I flushed the threads through with carburetor cleaner and tested for cleanliness by screwing a bolt into the hole, which was able to be inserted with ease.

Cylinder head internals

I bought a new wire brush and finished cleaning the old carbon from the combustion spaces. The engine is quite high compression for the design (7.5:1) and any glowing carbon deposits will cause preignition. Any lumps will also impede flow, which is already limited due to the design. There was quite a lot of carbon stuck to the head around the exhaust valve areas.

Protective coat of oil

Everything was them coated in thick oil to protect the now clean surfaces from rusting.

Wire brush to remove paint and rust

I began to clean the exterior surfaces of the head, as the paint was coming off in places.

Spark plug wells

The spark plug wells were thoroughly cleaned, as they were full of rust and engine grime.

Prepped cylinder head

With the entire cylinder head prepped by wire brush, I wiped it down with carburetor cleaner to remove the last of the oil and dirt.

First coatSecond coat

I had looked at the original colors these engines were painted. There is some consternation among the car club members as to which shade of blue or green or blue-green that should be used. Some people say the grass green color is correct, others the deep Brunswick green, others the mid blue-green. I decided to plump for a color called “deep turquoise”, which is close in hue to the blue-green used in the early to mid-50’s.

Delco R45 new vs. old comparison

I bought a replacement spark plug to get all the plugs matching AC Delco R45. Unfortunately the design has changed and the new plugs are smaller. I may end up ordering 7 more of the newer model.

Spark plug

Older Delco plug in the well of cylinder hole 8. I think I shall get some phenolic resin right-angled plug caps and make up some wires to go to the distributor.

View into the water distribution tube from the water pump

One of the last items to check was the water distribution tube. I had been advised to remove the water pump and inspect it, as the thing is made from thin sheet brass and they have a tendency to disintegrate. The function of this tube is to accept the water output from the water pump and flow out from there into the areas surrounding the exhaust valves. Therefore the hottest part of the engine is cooled first, with the water then circulating away around the rest of the engine before returning to the radiator to be cooled. Mine is in good shape, so now all I need is gaskets and some fresh oil to reassemble the engine. Then, the valve clearances need to be re-set accurately (this is easier with the engine out) and the engine portion of this is done.

When I removed the engine from the car, I had undone some of the cylinder head bolts in order to attach the lifting chains. As such, the whole lot needed to be slackened off and re-torqued down in the correct order.

Collection of head bolts.

The bolts were all very randomly tightened, mostly due to dirt and rust in the threads, by the feel of it. I decided to remove them all, take the head off, give it an inspection and clean, chase the cylinder head bolt threads through in preparation for refitting.

Block side of cylinder head.

The cylinder head came off without any trouble. It doesn’t appear to have been leaking badly and the deposits were a little dark but still within acceptable range.

Head gasket.

The head gasket is in moderately good shape, although it appears to have been reused a few times already. I think I shall be purchasing a replacement. The head and deck facing surfaces were a bit dirty. One valve was stuck open (far right in the image below, no. 8 exhaust), as the coolant gallery had weeped past the gasket, drawn in and made the valve stem rusty enough to stick. I coated it with penetrating oil, freed it up and now it operates correctly again. I had noticed one cylinder was down on compression the last time the engine was run- this will be why.

Cylinder block.

The deck itself appears to be in good order. The top is straight and level, though it required a clean. With no compression the engine turns over moderately smoothly. I think the bearings have been replaced without the crank having been ground. It feels a little tight between power strokes, indicating mild ovality of the crank journals. I can turn it over with my 8″ ratchet, so I’m going to leave it as-is because the oil pressure was very good and there are no other issues.

Hone marks on cylinder walls.

Two of the bores show fairly heavy hone marks still.

Worn shiny bore; 0.040 mark on piston crown.

The rest are quite mirrored but are not scored. All of the pistons are stamped 40 thou’ overbore.

Clean piston crowns- pots 4 and 5.

A rag with some carburetor cleaner on was all the pistons needed to come up clean. I do not think this engine has seen many miles since it was last apart.

Gasket scraper.

I started to clean the cylinder head up and came to a rapid halt- the blade in my scraper was no more good.

New tools.

I went to the store and bought some more tools- a box of 100 #9 razor blades for my scraper, a big wire brush to take the black paint off the engine and a tap set to chase out rusty and dirty bolt holes.

Making a start on cleaning the cylinder head faces.

With a new blade, I was able to start cleaning the cylinder head. In the image above, the baked-on dirt in the corner between the bolt hole and coolant passage is visible still. Although very fine, this is enough to cause a new gasket to weep.

I also made a start on de-coking the combustion chambers with a brass brush. It would appear that somebody had made a half-hearted attempt at it, but had missed a lot around the periphery, where the gas flow needs to be smooth and uninterrupted for good power and economy.

Clean cylinder head.

The cylinder head started to come up nicely. I ran out of time to do any more but initial impressions are good. There’s no pitting, marking, cracks or any other problems to be seen. It just needs meticulously cleaning and then it will be ready to refit.

Spray protectant.

I bought a can of heavyweight oil, designed to sit and prevent rusting up of the internals of an engine that’s to be lain up for winter. It also works well to protect engine surfaces that are left uncovered (bores and mating faces) while they are disassembled.

Coating the metal to protect it.

Everything was given a liberal coating of oil before being left to sit up overnight. More cleaning is due. The engine is going to receive a coat of paint also. It should be a deep green, the closest I can see it should be is Brunswick green. I may have to buy John Deere green and Ford blue engine paints and mix the color myself.

I jacked the car up to inspect the suspension and surrounding areas on this side. I also started to check for spiders and other biting creatures that may be inhabiting the dark, secluded spaces offered by the wheel wells and back of the radiator cowling.

Thankfully no critters were found. There was a lot of grime- mostly caked on dust, accumulated in old grease.

The car was pulled outside, jacked up and access was gained again by removing the road wheel.

Judicious use of my pressure washer saw a majority of the dirt removed from the underside. Inspection showed all of the metalwork in good condition, although a rub-down to remove surface rust and a new coat of paint are required.

The car was pushed back into the garage and the big drum fan put on in an attempt to dry the car out. This would later prove to have been moderately unsuccessful.

Final task of the day was to clean all the dirt liberated from the underside of the car off the driveway…

I then ended up spending yet more money. The purchase of a 2-ton engine crane, which helpfully folds up into a moderately small footprint.

At this point, work was halted as my (new) trolley jack decided to break. The handle came apart, the disc that the release lever fits into broke clean off.

My lifting chain was also in a worse state of repair- hanging outside but under cover, Louisiana’s climate has seen to the steel in an impressive fashion. There was no way I was going to trust that to lift nearly 900 lbs of metal.

Between times I made a start on removing the front grille and other items that were in the way of removing the engine.

The cross brace proved to be attached solidly to the front clip. I decided to remove the rivets holding it in, with them to be replaced later by bolts.

That just left the slam panel brace in place, which is held in with 4 large sheet metal screws.

I removed the pipework, clips, manifolds, fuel pump and carburetor from the passenger side of the engine.

Disconnected and tied up the accelerator and gear linkages on the driver’s side, removed the coil because it’s moderately loose in the holder (the original 6V coil was slightly larger in diameter).

A little while passed and a package arrived in the mail- the company who I purchased the jack from honored the warranty on it and sent a replacement handle.

This put the jack back into commission, and I tested to see if I could fit it under the back of the car and lift up on the base of the differential case. This was only successful if I first pump up the rear air suspension to raise the car a few inches.

Another special offer coupon arrived in the mail, so I purchased a load leveler to go with the engine crane. This added new chains and lifting eyes all in one go. I also bought a magnetic parts tray, as they are handy to have and it was $3.

I started the following weekend by raising the car up to see how well the jack fit with the leveler. The answer- just about!

I began to make preparation to remove the engine and gearbox. First task, remove the bolts from the front engine mount and clean them up.

Next, remove the last remaining obstruction on the front of the car.

Then, get up underneath and inspect the working conditions and how the propshaft comes off.

Next, remove even more spider webs. Last thing I wanted was to be sprawled under the car and have a spider decide to drop down onto me.

Then, put the back end of the car up on stands because the easiest method to remove the propshaft is to undo the bolts at the rear and slide the yoke off the gearbox end. The brown coloration on the underside of the vehicle is not rust- it is the color of the dirt where the car was previously driven in Mississippi.

I marked the position of the propshaft on the axle end, so it can be put back together in the same place.

The propshaft then pulled off the splines of the slip yoke and was set aside.

Upon jacking the front end of the car up, I discovered that the rear gearbox seal relies upon the slip yoke’s presence to be oil-tight. Not that it was particularly oil-tight when it was fitted, but this made it significantly worse.

I had wanted to push the car back a little before removing the engine but the front left brake had stuck on where the water had sat inside and rusted up the surface where the shoes were touching the drum. I decided I should have enough room, so began to connect up the chains to the engine, using the head bolts as attachment points as allowed in the manual.

I started to take the weight of the engine, then got up underneath and removed the rear engine mount and loosened the cradle. I also removed the speedometer drive cable from the back of the gearbox.

Up, up and away! Relatively painless removal with all obstacles not present.

Tilting the engine back to clear the oil pan put the gearbox at leaking-point. I deployed kitty-litter to the spill, which did a very good job of cleaning up the ATF.

There was a piece of flaky tape on the back of the gearbox, which I pulled off. Someone had masked up the data plate when they painted the gearbox, and never removed the tape. I assume that D51- indicates the gearbox was built in 1951.

Finally, the engine was set down on wooden blocks in a stable fashion on the floor. I am used to gearboxes dwarfing the engine, however in this case it is definitely the other way around, and that’s not because the gearbox is small!

I need to clean up a little, drain the fluids down and then investigate splitting the gearbox from the engine so I can work on rebuilding the valve block with new seals.

Continuing the trend, I made headway into removing ancillaries from the car.

Water pump.

The water pump boss was fitted with three loose studs and a bolt. I will check the threads and see if I can just refit bolts with non-slip washers.

Radiator brace.

After a bit of a clean with the vacuum cleaner, the front strengthening brace turns out to be riveted to a big U shaped channel that is screwed to the sheet metal as a strengthening shape. Next up will be to try and remove that, which will require cleaning and paint before refitting. Then I can see about removing the grille brace and then the grille itself. That will provide very good access to remove the engine.

Ancillaries being removed.

I removed the alternator and a few wires, which cleared up a lot of space. I shall not be refitting that alternator, instead I have my eye on an 85 Amp alternator that is mounted inside a housing that looks the same as the original generator dynamo.

Step one, remove the slam panel and strengthening bar. Discovered the bottom of the strengthening bar was not attached to anything. There’s also the remains of a sheared-off bolt stuck in one of the holes.

Strengthening rib, cut.

A previous owner had also decided to remove the engine- but there’s a strengthening rib in the way. It is held in with 8 coarse threaded bolts. 4 of them are small and attach in from the front, 4 are much larger and are accessed from up behind the headlights. Instead of undoing the bolts and removing the bar to gain access to remove the engine, someone decided to chop through the rib with a grinder and forcibly bend it out of the way. A genuine case of brute force and ignorance.

Up inside wheel well.

I took a brush and removed all the spider webs from up inside the wheel well. I carefully took a look for spiders but could not see any. The method here is to leave it a few days as the weather is mostly warm right now and see if any new webs are formed. That way I know I need to break out the bug spray before reaching up inside there to undo the bolts.

Radiator.

I found more metric bolts holding things in- in this case, the radiator. Cut the lower hose off, then fought at it with a pair of Channel-Lock pliers until it was free from the spigot. Fought with it, the fan shroud and the fan until it was safely removed. Fairly heavy staining shows it’s been leaking for a while, the green staining appears to be from the radiator cap, the neck is fractured where it screws on. The brown is more recent, there’s a pinhole where the core meets the top tank.

More empty space.

There’s a little bit more room now. I’m going to investigate removal of the strengthening bar, the top mount for the grille and the grille itself. That will open up a large amount of room to remove the engine without having to lift it up high.

Bolts stolen from the kids’ swing set, I think.

I left off at this point. I have concern over metric bolts with random washers, coming the wrong way out of the water pump pulley. The fan is a generic item, incorrect for the car. I may try find the correct one. Also, the thermostat is missing. I’m not sure what to think about that- either it was broken and they couldn’t find a replacement or it has been removed to gloss over an overheating issue. Time will tell.

Once the rust converter had dried, I painted the exposed areas with a superb color match. I looked at it this way, at least it’s blue.

Paint.

I took a slight diversion as I had stopped at the hardware store to get some stainless steel machine screws, as the front right indicator assembly had the wrong screws in and kept falling out, particularly so as I had added a seal which was padding it out.

Bulbs with new screws.

At the same time I found some old stock (probably twenty years or so) 2057NA bulbs, 5W/21W with self-colored amber glass.

Light fitting in place.

The screws, now not a mix of a wood-screw and a metric panel screw hold the light fixture correctly in place.

Orange parking light.

Illuminated, the assembly glows orange for parking lights and brighter orange for turn signals. The vehicle is grandfathered into the rules and is allowed to have white front turn signals due to its age, but people expect to see orange, so I shall use the orange bulbs. They can always be put back to white easily, just by changing the bulb.

Modifying the wiper arms.

I then turned my attention to the windshield wipers again. The arms appear to be generic replacement items and were set up very badly. They did not sit flush with the bottom of the screen and they overlapped the center divider of the windshield glass. I took them apart and removed just over an inch of the extendable arm.

Original versus modified.

I set the angle of the wiper blade to match the base of the windshield. The above picture shows how the wiper arms both were.

Correctly parked wiper arm.

The wiper arms were fitted and tuck down evenly with the base of the screen. I bought some rather old wiper blades from the local auto parts store that had been sat on a back shelf for years.

Wipers in operation.

The wipers wipe a short arc on the screen in operation, and tuck themselves down against the base of the glass when switched off. I may need to get a seal rebuild kit for the motor after all because it does like to stick and hisses without moving the arms.

I cleaned and straightened the vacuum lines. Unfortunately this one is a little short.

I removed the fuel/vacuum pump assembly also to try and determine why the device had been bypassed. It appears that the vacuum lines were bypassed for no good reason and the pipes cut, and the fuel pipe crimped connection seems to have broken off so that was cut up and the electric fuel pump added in its’ place. The fuel pump cleaned up nicely, the vacuum pump appears to work correctly.

Vacuum lines.

Finally, I decided to try and see how I could best route the vacuum lines. I think, after this exercise that I shall purchase some new metal line and create some all-new metal lines to the original specification, rather than try connect everything up with quarter inch rubber hose.

A brand new, 3-ton low-profile shop jack. It has the capacity and lift capability to raise the car up off the ground safely. My small trolley jack was not capable and did not fit under the car, as it was too tall.

Work started on the windshield wipers, which had never worked since I got the car. They would attempt to move a little bit but that was it. They would not stay running, instead would just hiss. With the wiring removed from up under the dash, access was significantly improved.

Remove wiper control knob.

First, the control knob for the wipers was removed. This has a small gearbox and a wire in a Bowden cable that runs to the wiper motor to actuate the valve.

Locking collar.

Knocked the locking collar off the control with a screwdriver. I’m not sure why there’s a large washer under the knob, I think this is incorrect.

Trico vacuum wiper motor.

The wiper assembly is manufactured by Trico. I’d never taken one of these apart before, so a learning experience in vacuum motors was to be had.

Flip-flop valve assembly.

The side panel came off to reveal a spring-loaded flip-flop that’s activated by the motor spindle when it reaches the end of its travel, and a plastic valve that directs the vacuum to one of two ports at a time.

Wiper motor apart.

The wiper motor is predominantly made from the semicircular lower section. A flap is drawn from side to side, and the grease inside forms a seal. The grease had dried up and the seal was poor. I cleaned everything out and re-greased it.

Oiling the Bowden cable and gearbox.

The Bowden cable was stiff to operate. It had a couple of kinks in which I straightened out between my fingers, and it was oiled and left to soak. This significantly improved its’ function.

Vacuum pipe, polished.

Because it was out, I polished the pipe that takes the vacuum. Sadly someone has shortened it, so it may be changed again for a new stainless pipe.

Reassembled and tested wiper motor.

The motor was reassembled and tested. It operates smoothly and with significant force. The self-park also works- in operation the wipers will wipe an arc on the screen away from the edges, switched off they tuck themselves down tightly against the frame of the window.

Access to wiper spindle.

The wiper arms, now disconnected from the wiper motor were difficult to move, particularly the driver’s side. With the dash removed, access to undo the wiper mechanism is good, so I undid the driver’s side spindle clamp.

Escutcheon removal.

Breaking the old seal, I removed the wiper escutcheon and linkage from the car.

Driver’s side wiper linkage.

Lain out, the assembly is in remarkably good condition, just dirty. I tried to move the spindle by hand and it was very difficult.

Penetrating oil to remove dirt and rust.

I soaked the spindle down with penetrating oil, which washed out a lot of dirt and rust. I then finished up with regular engine oil which made the assembly easy to turn.

Cleaned and lubricated spindle.

It was left to sit for the night and drain down.

Driver’s side wiper hole.

I cleaned up the hole left by the mechanism. There’s a little rust which will require treatment before reassembly.

Glove box.

I then fought with the glove-box. It is a hardboard affair, held in place by screws. Removed, access to the passenger-side wiper mechanism is straightforward.

Hole at bottom of thread.

Inspection of the passenger side escutcheon showed something I hadn’t spotted on the driver’s side because it was obscured by dirt- a slight drill-through from the screw-hole that the mounting bolt fit into, through to the inside of the shaft area.

Squeezing grease into screw-hole.

I began by squeezing grease into the screw hole.

About to force grease down with bolt.

Then, forced the grease down by screwing the mounting bolt into the hole. This was successful until the interior filled with grease, whereby more grease would escape through the threads of the bolt than was forced through the bearings.

Grease nipple fitted.

I had a thought and went offered the mounting bolt up against one of the grease nipples on the front suspension. It looked to be about right so I undid it and fitted it to the wiper linkage. A perfect fit.

High pressure grease gun.

Grease gun fitted to the nipple, and fresh clean grease pumped into the assembly under significant pressure.

Dirty grease expelled.

This started to force dirt and rust out through the bearings. Rotating the spindle back and forth proved an effective way to clear the bearings out.

Lubricated assembly.

All cleaned up and free to turn, I turned my attention to the seals. New ones are available but I had bought some high density foam rubber to repair the rear light seals on the Renault a while back.

Paper template.

Cut out some paper and made a pencil rubbing of the edge of the mounting hole in the top of the scuttle.

Cut out and transferred the shape to foam, trimmed everything up to fit.

Seals fitted.

Both linkages fitted with seals. If these don’t work I’ll get some proper ones.

Rust converter.

Final thing was to apply some rust treatment to the exposed metal. That’ll dry thoroughly, receive a little paint and have the wiper assemblies refitted.

I refitted the now-clean headlight switch back to the dash. Unfortunately now the rest of the dash dials look dirty in comparison. I shall have to remove the heater controls and clean them also.

Headlight pull-switch (in second position)

Electrical work continued with gauges. The fuel gauge was similarly burned up inside, along with the temperature gauge. Measuring the diameter of the wire on the fuel gauge coils showed it was the same diameter as the new wire I had bought.

Measuring wire gauge with micrometer.

The mounting bucket was also showing signs of age; the paint was flaking off from heat and there were scorch-marks one the paint also. Cleaned down the original paint (which came off very easily with carburetor cleaner).

Clean mounting bucket.

Counted the number of turns on the fuel gauge and re-wound the spool carefully. Testing on a battery with 6V converter in place- I decioded to use 6V because the wire gauge was the same as original, lower current through the sender in the tank and everything could be set up identically to how it was removed.

I then began to readdress the temperature gauge. Operating it at 6 Volts showed there was insufficient magnetic flux in the middle of the needle’s range to hold it in place over the friction of the pivot.

Six volt test.

Operating it at 12V as originally intended solved this but I had wound the coils for the original spec sender unit, which is no longer available. The original sender unit had a very low range of resistance values for temperature, 100F being about 300 Ohms. I purchased a (slightly) more modern sender, a Wells TU-4. It has approximately twice the resistance per temperature, is physically the same size and is more readily available, as it fits mid 50’s Chevy trucks.

Sender unit in hot water, with thermometer.

I decided to abandon attempting to calibrate the gauge while connected and instead started plotting temperature versus resistance on paper.

Wells TU-4 resistance curve.

The gauge is wired in a Y-configuration- I had missed this previously. One coil is directly across the supply voltage, the other is across supply through the sender. I decided that I should be able to add a resistance across the other coil and reduce the pull of the magnetic field, allowing the higher resistance (and lower current) of the modulated coil to pull the needle off COLD sooner.

Bench testing to determine biasing resistance.

Initial testing proved successful, with the gauge capable of being adjusted to be accurate from the lower end of the range all the way up to maximum. It over-reads a little between 100-130F but is accurate at 180F and 230F. I decided knowing if the engine was too hot was more important to know if it was cold.

Resistance in place, heat-gun testing with sender unit.

Reassembled into the frame and tested the gauge again using the frame’s ground, as occurs in the car. Successful testing with good results.

Gauge mounted in dash.

I turned my attention to the paint on the dash, which was scratched and thin in places from years of polish and being handled. I started by stripping all the gauges out and taking the old paint off with a brass brush.

After removing the wiring from the engine bay, I started work on removing the old wiring from under the dash.

Spaghetti. Old, dusty spaghetti.

I removed the fuse box. Under the dash should be significantly more tidy than it is; a lot of the wires had been pulled down out of the loom and were just left to dangle. I also undid the three-set of gauges from under the dash, as there is no real reason to have them there.

Trio of unnecessary gauges.

I heated the bulb of the temperature gauge with my hot air gun to test it. Still, good, it may end up in another application. The oil pressure gauge worked fine so found a home on my lawn tractor. The ammeter, which had never really read much at all was connected incorrectly (in line from the alternator) which would explain the lack of movement.

Plug.

I filled the hole from the oil gallery where the old takeoff pipe was for the oil pressure gauge, until I have a replacement pipe. This is simply so I do not empty the oil pan all over the floor when I spin the engine over.

The fuse box (and lid, found under the driver’s seat, sadly covered in paint) is quite comprehensive for the age of the car.

The dash looks better without the gauges, the engine compartment is similarly tidy. I need to investigate the wiring that goes downward under the body as all the wires destined for the back of the car run up above the driver’s head.

The amount of wires in the pile, steadily growing. This represents most of the wire from the fuse box and under the dash.

The dash cluster is held in with 4 nuts, moderately accessible from up underneath.

I clipped the wires from the back of the dash to provide better access and removed the cluster.

Not a reproduction item. January 1951, and they had built 4000-odd cars by that time. Needed to be ready for the new model year!

Further disassembly of the gauge cluster to remove the side gauges and clean the perspex lenses. Over the years they have been wiped a lot of time and have become scratched. On the inside, a fine haze was apparent.

Part the way through, to show comparison of clean versus dirty lenses.

The reason for the haze on the lens would become apparent later on.

The speedometer frame had ghostly images of the numbers, faded into the paint. A little polish saw the paint clean again.

Gently buffing the scratches out of the speedometer face with my polishing wheel in my twist drill.

All clean! The improvement is immediately visible. I still need to take it apart and redo the satin black paint where it has all rubbed off over the years.

I connected my air line up to the oil pressure gauge. It’s a mechanical, Bourdon-tube device. It still registers correctly.

I then tried connecting up the other gauges to a 6V power source to test if they were still operational. Quick testing with a multi-meter showed both had at least one failed coil. The haze on the inside of the lens was from the enamel insulation on the wire having caught fire. Previous owner had connected the dash up to 12V when they did the conversion. That must have liberated quite a lot of smoke- and will be the reason for the additional gauges.

Luckily the coils are secured to the armature with nuts and bolts. I removed one coil. The failure is easy to see.

I modified my twist drill to have a cammed section on the chuck (made from electrical tape) that would operate a microswitch every revolution. The switch then in turn operates a small mechanical counter.

Counted the number of turns of wire on the bobbin. It had burned up and split in three places.

Took my micrometer and meaured the diameter of the wire. 7.2 thou’, which is 33AWG. Being as the gauges were both inoperable due to having been burned up, I decided to re-wind them for 12V instead.

36AWG enameled copper wire, with half the cross-sectional area of 33AWG, and twice the resistance per foot. Winding twice the number of turns of this onto the bobbin will make it suitable for 12V operation.

I stripped the enamel off the end of the wire with sandpaper, then checked the end of the wire for good continuity with my meter. This end contacts directly to the metal of the coil bobbin.

Carefully wound the wire on. This was a moderately slow procedure because I was manually guiding the wire as it wrapped and the cam operates only briefly so the counter is not actuated enough to count over about 100RPM.

Tested the end to end resistance of the coil. 26 Ohms, in the correct ball park expected from this gauge of wire.

The second coil, which did not catch fire but charred significantly was also removed.

It was unwound- this side has more turns.

Again measured to make sure it was the same gauge of wire.

Carefully wound on, counting every turn, trying to make the winding even. Nearly out of space!

Tested for resistance- the number of turns being more, the longer the wire and the greater the resistance.

Fitted both coils back into the armature and soldered them to their pegs.

Through a moderate resistance, the gauge now reads properly! I need to calibrate it- the service manual provides the curve of the thermistor in the engine bay per temperature. I can take the three calibration points (at the top of the scale) and set the coils up accordingly. They are adjustable on slides to set the gauge up to read the correct deflection per current passed.

The frame the gauges connect to was a little worse for wear. It wasn’t painted very well to begin with, the brown staining from where the gauge had burned was evident and the heat from the dash illumination had made the paint in that vicinity all flaky, which was getting onto the inside of the lenses as I moved the dash about.

I rubbed the old paint back, to remove loose paint and provide a good keyed surface.

A couple of coats of Rustoleum Heirloom White later (a remarkably good color match) and the frame is looking really nice.

At the same time I heated up the paint and windscreen washer bottle holder (the evening was a cold one, not far from freezing) in prep for paint.

A nice gloss Sky Blue. The frame should have a yellow sticker on the front for screen-wash instructions.

While that was drying I vacuumed, shampooed and generally cleaned up the back of the passenger cabin.

I was puzzling over the headlight switch. I needed to remove it from the dash as it was stiff to operate. However, I couldn’t figure out how to pull it out. The knob wouldn’t fit through the escutcheon after the mounting screw was undone.

Turns out there’s a spring-loaded pin in the back of the mechanism that presses a spring-loaded collar out of the way and allows the entire knob and shaft assembly to be pulled from the switch.

I took the switch to pieces, lubricated and cleaned it as all the old grease had dried up and was more of a hindrance than a help. Sadly the rheostat is only a few ohms, designed to dim a fairly heavy load (10 4W bulbs), and will have very little effect on the LEDs that have been retrofitted. At least it can be used to turn the dash on and off.

I polished the plastic and chrome, cleaned the grip with a brass brush and polished the locking screw as it is visible when the switch is pulled out. Not bad looking now.